Eratosthenes called this the Great Fish and said that it was the parent of the
two smaller fishes of the zodiacal constellation Pisces. Like Pisces, its
mythology has a Middle Eastern setting that reveals its Babylonian origin.
According to the brief account of Eratosthenes, the Syrian fertility goddess
Derceto (the Greek name for Atargatis) is supposed to have fallen into a lake
at Bambyce near the river Euphrates in northern Syria, and was saved by a large
fish. Hyginus says, in repetition of his note on Pisces, that as a result of
this the Syrians do not eat fish but they worship the images of fish as gods.
All the accounts of this constellation’s mythology are disappointingly sketchy.

Bambyce later became known to the Greeks as Hieropolis (meaning ‘sacred city’), now called Manbij. Other classical sources tell us that temples of Atargatis
contained fish ponds. The goddess was said to punish those who ate fish by
making them ill, but her priests ate fish in a daily ritual.

According to the Greek writer Diodorus Siculus, Derceto deliberately threw
herself into a lake at Ascalon in Palestine as a suicide bid in shame for a
love affair with a young Syrian, Caystrus, by whom she bore a daughter,
Semiramis. Derceto killed her lover and abandoned her child, who was brought up
by doves and later became queen of Babylon. In the lake, Derceto was turned
into a mermaid, half woman, half fish.

A common alternative name for the constellation was Piscis Notius, used by
Bayer, Hevelius and Bode. John Flamsteed, though, preferred the title Piscis
Austrinus in his star catalogue (1725) and atlas (1729) and his choice
eventually prevailed.

Piscis Austrinus, called Piscis Notius on the Uranographia of Johann Bode
(1801), is shown lying on its back and drinking water from the urn of Aquarius.
In its mouth is the bright star Fomalhaut.

Stars of Piscis Austrinus

Piscis Austrinus is more noticeable than the zodiacal Pisces because it contains
the first-magnitude star Fomalhaut. This name comes from the Arabic fam al-hut meaning ‘fish’s mouth’, which is where Ptolemy described it as lying. In the sky the fish is shown
drinking the water flowing from the jar of Aquarius, a strange thing for a fish
to do. The flow of water ends at Fomalhaut, which Ptolemy regarded as being
common to Aquarius and Piscis Austrinus. Bedouin Arabs visualized Fomalhaut and
Achernar (in Eridanus) as a pair of ostriches. The name Fomalhaut is sometimes
mis-spelt “Formalhaut”.

In the Almagest, Ptolemy listed six additional stars in this area that did not form part of
Piscis Austrinus; these are now assigned to the modern figure of Microscopium.
In addition, when the 12 new southern constellations of Keyser and de Houtman
were invented at the end of the 16th century, the star that Ptolemy placed at
the tip of the fish’s tail was appropriated for use as the head of the new constellation Grus, the
crane; it is now known as Gamma Gruis.

Chinese associations

Chinese astronomers called Fomalhaut Beiluo shimen, the gate to the encampment of Yulinjun, the Royal Guards, a large constellation to the north of it. Epsilon and Lambda
Piscis Austrini, along with another two or three fainter members of Piscis
Austrinus, were part of Yulinjun, most of which was in Aquarius. Delta Piscis Austrini was Tiangang, ‘celestial net’, representing tent-making facilities for the military camp.

Gamma Piscis Austrini plus three other stars, possibly including Gamma and
Lambda Gruis, formed Baijiu, a bowl or tub, said by some to be for waste disposal. Ten stars including Mu,
Theta and Iota Piscis Austrini formed Tianqian, ‘celestial money’, interpreted variously as coins or paper money; one interpretation says it was
paper money to be burnt in Baijiu to appease ghostly spirits.